Modern electronic instruments produce signals that are passed through a chain of electronic effect generators before being amplified and passed to a speaker system. These electronic effect generators alter the final output sound by modifying properties such as frequency response, overall amplitude, envelope characteristics, echo and sometimes introducing a specific type of distortion.
The prior art provides a musician with control over these properties with knobs, pressure pads, pedals or the selection of pre-defined musical characteristics ("sound patches"). Most musical effect generators alter musical qualities on time scales that span several notes and do not vary within a phrase or note. The relatively clumsy controls associated with these devices have heretofore provided adequate control over musical parameters of these effects at the expense of playing technique.
For example, pedals are used to vary the electronic effects such as distortion, echo or `wah-wah`. These pedals are operated by a musicians's food and do not provide sensitive control. One device that improves on the standard pedal design is disclosed in U.S. Pat. No. 5,079,536.
Mod wheels are essentially large dials or knobs which generate signals that affect parameters of electronic musical effect generators (i.e., volume or frequency response). Pressure pads measure the pressure applied to a specific point on an instrument, and can be used to control musical parameters. Piezo-electric technology has also been employed to provide touch sensitive characteristics to the keys and is disclosed in U.S. Pat. Nos. 4,558,623 and 4,979,423. While both mod wheels and pressure pads are currently used as parameter controllers (i.e., a MIDI continuous controller) in keyboard instruments, they have a relatively minor impact on playing technique and neither provides the intuitive and sensitive control that is desired. Hence, widespread use of mod wheels and pressure pads on instruments other than keyboards is rare.
The present use of mod wheels and/or pressure pads substantially affects traditional playing technique in guitar-like instruments. For pressure pads, special consideration must be made of the dependency of slight variations in hand placement, while maintaining sensitivity to slight changes in applied pressure. One patent that teaches this approach is U.S. Pat. No. 4,630,520. A patent that employs a strain gauge for parameter control in a guitar-like instrument, is U.S. Pat. No. 4,653,376. However, in this patent the application of strain measurement technology is limited to measurement of string tension.
Another patent U.S. Pat. No. 4,503,746 proposes control of musical parameters in a guitar-like instrument. It employs a Hall effect transducer to measure the force that a musician applies to a shoulder strap. It provides only an indirect linkage between applied force and transducer deflection and its focus is limited to tension measurement in the shoulder strap. Additionally, the tension in the shoulder strap cannot be effectively controlled by the picking hand.
One patent that teaches the use of the guitar pick as a control means is U.S. Pat. No. 4,234,144. It employs a contact switch to determine the exact time that the guitar pick strikes the strings. This control is then used to initiate a predetermined effect as well as increment a strike counter that controls an overall variation of a `special musical effect` over several notes. As for the case in keyboard based parameter control, no prior art in parameter control for guitar-like instruments provides the intuitive and sensitive control that is desired.
Strain gauges are also employed in guitar-like instruments to translate the vibrations of strings to electrical signals. Patents that teach the use of strain gauge technology to translate acoustic vibrations into electrical signals are U.S. Pat. Nos. 4,228,715 and 4,292,875. Additionally, patents U.S. Pat. Nos. 5,123,325 and 5,123,326 employ piezo film as acoustic/electric transducers, but do not address the issue of parameter control via strain measurement.
One patent that teaches the use of fiber optic technology in parameter control via strain measurement is U.S. Pat. No. 5,046,394. This work measures the deflections of a glove outfitted with fiber optics. In the context of the present invention, this work has several drawbacks:
1. An inconsistent relationship between optical fiber deflection and finger movement, PA1 2. A dependency on hand orientation that severely impacts playing technique, and PA1 3. A lack of tactile feedback that doesn't interfere with playing technique (i.e. a small mechanical resistance proportional to finger deflection).
The present invention provides an intuitive, sensitive device for controlling musical qualities of electronic instruments without affecting the fundamental playing technique of the musician.